It seemed as if the relationship between Kyōsuke and his sister, now fourteen, would continue this way forever.
One day however, Kyosuke finds a DVD case of a magical girl anime which had fallen in his house's entrance way.
, is a Japanese light novel series written by Tsukasa Fushimi, with illustrations provided by Hiro Kanzaki.
has not gotten along with his younger sister Kirino in years.For longer than he can remember, Kirino has ignored his comings and goings and looked at him with spurning eyes.Kyosuke dates Ruri during summer vacation but she breaks up with him.However, in the Oreimo: Kuroneko spin-off manga, the two wind up together ten years later.Although she states that she only likes eroge because of their cute characters, she shows a perverted side of herself when playing those games.
She uses the screen name Kiririn when with her otaku friends.He decides to become more of an older brother to her.Despite Kyosuke being older, his sister is generally the dominant person in their relationship, with Kyosuke only standing up to her in truly serious situations.To Kyosuke's surprise, he finds a hidden eroge inside the case and he soon learns that both the DVD and the game belong to Kirino.That night, Kirino brings Kyosuke to her room and reveals herself to be an otaku with an extensive collection of moe anime and younger sister-themed eroge she has been collecting in secret.Kyosuke quickly becomes Kirino's confidant for her secret hobby.